Apparatus for heating blast furnace stoves



March 26, 1963 G. H. KRAPF APPARATUS FOR HEATING BLST FURNACE STOVES Filed Decy 21. 1960 vm. Nh

3,082,995 APPARATUS non HEATING BLAST FUaNAca This invention relates to apparatus for heating stoves and particularly blast furnace stoves. The conventional blast furnace stove contains within the stove shell a combustion chamber extending from the top to the bottom of the stove shell. Attached to this combustion chamber is a gas furnace burner which mixes the gas and air and `delivers this mixture into the combustion chamber where the fuel is burned. The combustion space occupies approximately 40% of the horizontal section within the stove shell so that the volume of stove checker brick that can be installed within the shell of the stove is reduced accordingly. In the past, attempts have been made to burn the blast furnace gas outside of the stove shell and to put the products of combustion into the dome of the stove. However, these attempts have failed for various reasons, including high installation cost, high maintenance cost `and poor control of temperatures. It is also common to have the products of combustion pass through the stoves at atmospheric or essentially atmospheric pressures.

It is therefore an object of my invention to provide blast furnace stoves in which the majority of the space within the stove shell is utilized for checker work and in which the fuel is burned outside the stove with the products of combustion being introduced into the top of the stove.

Another object is to provide such a blast furnace stove in which the flow and temperature of the burnt gases is accurately controlled.

Still another object is to provide such a blast furnace stove in which the burnt gases are utilized to drive a gas turbine.

A further object is to provide such a stove in which the burnt gases are maintained at an elevated pressure within lthe stove.

These and other objects will be more apparent after referring to the following specification and attached drawing, in which:

FIGURE 1 is a schematic view of a blast furnace stove equipped with the apparatus of my invention; and

FIGURE 2 is an enlarged sectional view of :a detail of my invention.

Referring more particularly to the drawings reference numeral 2 indicates the shell of a -blast furnace stove. Checker brickwork 4 is installed in the shell 2 across the full cross section thereof and extends from a point adjacent the bottom of the shell to a point adjacent the top thereof. A space 6 is provided beneath 4the brickwork 4 and a space 8 above the brickwork. 'Ihese spaces are kept at a minimum and are only suiicient to provide for the necessary conduit connections. The brickwork 4 is supported in any suitable manner such as by means of refractory arches. A cold air conduit 16 is connected to the bottom of the shell 2 into the space 6 and a conduit 12 is connected below the conduit 10. Shut oif valves -14 and 16 are provided in the conduits 1t)` and 12, respectively. A hot air conduit 1S is connected to the shell 2 into the space S. A shut oft valve 20 is provided in the conduit 18. A cold air conduit 22 having a control valve 24 therein is connected in the conduit 18. A temperature responsive device 26 is provided in the conduit 18 and is connected to a control 2S which regulates the valve 24. An opening 30 is provided in 3,6Z Patented Mar., 26, 1933 dome 32 of `the shell 2 and a combustor 34 is mounted on top of the dome 32 over the opening 30. A shut olf valve 36 is provided to close the opening 36. The combustor is a device wherein fuel is :substantially all burned prior to its discharge therefrom. As shown combustor y34 consists of an outer shell 38 and a concentric inner shell basket 40 having openings or slots 42 therethrough. Combustion air is delivered into the space between the shells 38 and 40 through a conduit 44 having a shut off valve 46 therein. Preferably at least two openings are provided in shell y38 so as to provide for air flow around the shell 40. Fuel, preferably blast furnace gas, is introduced into the top of the inner shell 45t through a conduit 4S having a shut off valve 50y therein. Pilot fuel is introduced into the top of the combustor 34 through a conduit 52 having a shut off valve 54 therein. An igniter 56 is provided at the end of the conduit 52. Additional burners 57 may be provided at the top of combustor 34 for the introduction of auxiliary fuel when necessary. Combustion air is provided to the conduit 44 by means of an air compressor 58` and fuel is provided through the conduit 48 by means of a compressor 60. The compressors SS and 6tl are preferably of the axial ow type and are driven by means 'of a motor 62 and gas turbine 64. Inlet 66 of gas turbine 64 is connected to conduit 12. A branch conduit 68 is connected to inlet 66 and control valve '7G` is provided therein. A control valve 72 is mounted in conduit 12 on .the stack side of gas turbine inlet Conduit 66. A control 74 is provided to operate the valves 70 and 72. A shut off valve 76 is provided in inlet conduit 66. A regulating valve 78 is provided in the conduit 12 on the stove side of inlet conduit 66. The position of valve V78 is controlled by means of a pressure -control 86 hav- 'ing a pressure tap 82 connected to the conduit 12 on the stove side of valve 78. Pressure tap 82 may alternatively be connected to the bottom of the stove. A thermocouple or other temperature responsive device 84 is provided at the top of the checkerwork 4 and is connected to a control 86 for a valve 88 located in recycle conduit 90. A- heat exchanger 92 is also provided in the conduit 90. A conduit 94, having a regulating valve 96 therein, connects conduits 44 and 66. The valve 96 is positioned by means of a control 98 lwhich has a connection 166 to a vflow determining meansv 162 in conduit 44 adjacent the compressor 5'8.

The compressors 58 and 60, gas turbine 64 and motor 62 may be used in conjunction with more than one stove. For that purpose conduit 44 has a -branch conduit 44 leading to a ysecond stove (not shown) with a shut off valve 194 being provided in the branch conduit 44'; the conduit 48 has a branch conduit 48 connected to the second stove with a shut oif valve 106 being provided in the branch conduit 48'; and conduit 66 has a branch conduit 66' leading to the second stove with a shut off valve 168 being provided in the branch conduit l66.

A thermocouple 11d` or other temperature determining means is preferably provided in the space 6.

Assuming that blast air has been passing through the stove 2 and the temperature of the checker work therein has fallen to a point where .the checkerwork 4 must be heated, the valves 14 and 20 are closed to stop the flow of :air therethrough. lf the air and fuel compressors 58 and 6i) have been operating to heat another stove they are disconnected from that stove by closing valves 164, 106 and 108. If .the motor 62 has not been operating it is started in operation to run compressors 58 and 60. Valve 88 is partially opened so that the fuel being compressed will flow around the control loop, including heat exchanger 92. During this time the position of valve When a pilot flame is established as indicated by a standard flame detection device, not shown, the ignitor '56 will be .deenergized Blast furnace gas or other fuel is 4then admitted to the combustor 34 by opening valve S0. The amount of blast furnace gas furnished is established by setting valve 88 to the desired position. The combustor and stove are then brought to a pressurized condition by increasing the tlow lof blast furnace gas and air to the combustor 34 by -furtheradjustment of valves 88 and 96 and by gradual movement of control valve 78 toward a closed position as determined by the pressure in conduit 12 until the desired pressure of at least two atmospheres absolute/is obtained. The pressure is preferably maintained between two and four atmospheres absolute. The control 9S is set to deliver a ture adjacent the bottom thereof below the checkerwork, a valve for controlling flow of air through said first conduit intosaid structure, a second conduit opening into said hollow structure adjacent .the bottom thereof `below the checkerwork, a valve for controlling flow of burnt gases from said structure through 4said second conduit, a third conduit opening into said hollow structure above said checkerwork, avalve for controlling ow of heated .air from said structure through said third conduit, said hollow Structure having an upwardly extending opening through the top thereof, an inner shell basket mounted on top of said hollow structure around said opening with `its axis substantially vertical, said inner shell basket having openings through its wall, an outer shell mounted on top of sai-d hollow structure around said inner Ishell basket concentric therewith, a conduit for delivering fuel to the top of said inner shell basket, a conduit for delivering combustion air to the space between said inner and `outer shells adjacent the top thereof,

Yand Valve means between said inner basket and the hollow structure. Y

2. A blast furnace stove according .to claim 1 including a pilot burner at the top of said inner shell, a regupredetermined flow of air to the combustor 34 and the desired heat input to the combustor is automatically controlled by the temperature sensitive device 84. During this period of initial operation control valve 7G will be gradually opened to atmosphere to satisfy the needsv of the gas turbine 64.

To place the gas turbine 64 in operation, valve 76 is opened and valves 76 and-72 gradually closed by means of control 74. This will cause dow of burnt gases .through conduit l66 to the gas turbine 64 so as to produce at least part of the energy required to operate :the compressorsSS and 6). When the stove 2 has reached the desired temperature as indicated by the temperature sensitive device llltl the fuel is taken off by closing Valves 50 and 54. The air is then taken off and the stove 2 isolated from the combustor 34 by closing valves 36 and 46. Valves 16 and 76 are Aalso cio-sed. Valves lli and 20 are then opened to permit flow of cold air through the stove 2 where itis heated and then delivered Ythrough conduit 18l to the blast furnace. 'Ille temperature of `the air delivered to the blast furnace is controlled by the opening or closing of valvel 24Y by means of control 28 so as to admit more or less cold air through conduit ZZ. If the compressor-turbine set is not to be used with another stove the motor 62 is shut oif. If theV set is to be used with another stove theV motorm62 can continue to operate and valves 104, 106 and 168 opened to the other stove. t

While one Yembodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of .the following claims.

I claim:

lating valve for controlling flow of fuel in said fuel conduit, a regulating valve for controlling Aflow 0f air in said combustion air conduit, a temperature responsive device at the top of said checkerwork, and means controlled by said temperature responsive device .to control said fuel regulating valve.

3. A blast furnace stove Vaccording to claim 1 includ- Ving a regulating valve for controlling ow of fuel in said fuel conduit, a regulating valve for controlling llow of air in said combustion air conduit, a compressor for supplying fuel to said fuel conduit under pressure, a compressor 4for supplying air .to said fuel conduit under pressure, and means for positioning the valve in said second conduit to maintain the burnt gases in said structure at a pressure substantially above atmospheric.

4. A blast furnace stove according to claim 3 including a gas turbine connected to drive at least one of said compressors, a conduit leading 4from -said second conduit to the inlet of said gas turbine, and means for controlling flow of burnt gases from said second conduit to 1. A blast furnace stove comprising a hollow strucl ture, checkerwork in' said structure extending from a point adjacent the bottom thereof to a point adjacent the top thereof, a tirst conduit opening into said hollow struc- References Cited in the le of this patent UNITED STATES PATENTS 341,285 Siemens May 4J 1886 912,967 -Larimer Feb. 16, 1909 1,531,648 Dyrssen Mar, 31, 1925 1,535,146 Brassert et al. Apr. 28, 1925 1,724,848 McGee ,.i Aug. 13, 1929 V1,941,446 Isley Dec. 29, 1933 1,942,762 McGee Jan. 9, 1934 2,163,762l Noack et al June Y27, 1939 annif/t2k Baumann et ai. july 4, 1939 2,223,572 Noack et al. Dec. 3, 1940 2,840,362 Krieble et al June 24, 1958 2,944,806 Carter July 12, 1960 

1. A BLAST FURNANCE STOVE COMPRISING A HOLLOW STRUCTURE, CHECKERWORK IN SAID STRUCTURE EXTENDING FROM A POINT ADJACENT THE BOTTOM THEREOF TO A POINT ADJACENT THE TOP THEREOF, A FIRST CONDUIT OPENING INTO SAID HOLLOW STRUCTURE ADJACENT THE BOTTOM THEREOF BELOW THE CHECKERWORK, A VALVE FOR CONTROLLING FLOW OF AIR THROUGH SAID FIRST CONDUIT INTO SAID STRUCTURE, A SECOND CONDUIT OPENING INTO SAID HOLLOW STRUCTURE ADJACENT THE BOTTOM THEREOF BELOW THE CHECKERWORK, A VALVE FOR CONTROLLING FLOW OF BURNT GASES FROM SAID STRUCTURE THROUGH SAID SECOND CONDUIT, A THIRD CONDUIT OPENING INTO SAID HOLLOW STRUCTURE ABOVE SAID CHECKERWORK, A VALVE FOR CONTROLLING FLOW OF HEATED AIR FROM SAID STRUCTURE THROUGH SAID THIRD CONDUIT, SAID HOLLOW STRUCTURE HAVING AN UPWARDLY EXTENDING OPENING THROUGH THE TOP THEREOF, AN INNER SHELL BASKET MOUNTED ON TOP OF SAID HOLLOW STRUCTURE AROUND SAID OPENING WITH ITS AXIS SUBSTANTIALLY VERTICAL, SAID INNER SHELL BASKET HAVING OPENINGS THROUGH ITS WALL, AN OUTER SHELL MOUNTED ON TOP OF SAID HOLLOW STRUCTURE AROUND SAID INNER SHELL BASKET CONCENTRIC THEREWITH, A CONDUIT FOR DELIVERING FUEL TO THE TOP OF SAID INNER SHELL BASKET, A CONDUIT FOR DELIVERING COMBUSTION AIR TO THE SPACE BETWEEN SAID INNER AND OUTER SHELLS ADJACENT THE TOP THEREOF, AND VALVE MEANS BETWEEN SAID INNER BASKET AND THE HOLLOW STRUCTURE. 